| 摘要 |
An abrupt fall in a current value immediately after an abrupt rise at the time when an starting switch (47) is turned ON is detected, when the current value rises due to starting of nut fastening and then the current value abruptly falls, it is determined that an inward flange (26) of a washer (25) is sheared, and when the current value reaches a value corresponding to a primary fastening torque, the motor (15) is stopped. |
